1. Field of the Invention
The present invention relates generally to the fields of cellular biology and the diagnosis of neoplastic disease. More specifically, the present invention relates to an extracellular serine protease, termed tumor antigen-derived gene 15 (TADG-15), which is overexpressed in carcinomas.
2. Description of the Related Art
Extracellular proteases have been directly associated with tumor growth, shedding of tumor cells and invasion of target organs. Individual classes of proteases are involved in, but not limited to, (a) digestion of stroma surrounding the initial tumor area, (b) digestion of the cellular adhesion molecules to allow dissociation of tumor cells; and (c) invasion of the basement membrane for metastatic growth and activation of both tumor growth factors and angiogenic factors.
In the process of cancer progression and invasion, proteases mediate specific proteolysis and contribute to the removal of extracellular matrix components surrounding tumor cells, the digestion of intercellular adhesion molecules to allow dissociation of malignant cells and the activation of many growth and angiogenic factors.1-3 Depending on the nature of their catalytic domain, proteases are classified into four families: serine proteases, metalloproteases, aspartic proteases and cysteine proteases.3 Among these proteases, the metalloproteases have been well studied in relation to tumor growth and progression, and they are known to be capable of degrading the extracellular matrix, thereby enhancing the invasive potential of malignant cells.1,4,5 For serine proteases, previous studies have demonstrated an increased production of plasminogen activator in tumor cells and a positive correlation between plasminogen activator activity and aggressiveness of cancer.6,7 Prostate specific antigen (a serine protease) has also been widely used as an indicator of abnormal prostate growth.8 More recently, several other serine proteases have been reported, viz. hepsin and the stratum corneum chymotryptic enzyme (SCCE), which are overexpressed in ovarian cancer and which may contribute to malignant progression by increasing the extracellular lytic activity of these tumor cells.9 
The prior art is deficient in the lack of effective means of screening to identify proteases overexpressed in carcinoma. The present invention fulfills this longstanding need and desire in the art.